It is generally recognized that there is a need to be able to accurately determine the brake stroke condition on a vehicle's brakes, so as to ensure the timely maintenance of the vehicles' braking system. As most braking systems are difficult to inspect for the brake stroke condition, many operators of vehicles, such as trailers and trucks, let the maintenance of the brakes lapse which can result in a loss of brake effectiveness.
Prior art adjustment indicators have been devised to address the aforenoted problems. For example, U.S. Pat. No. 4,279,214 issued Jul. 21, 1981, discloses a brake adjustment indicator which can be installed on a vehicle with pneumatic brakes. The indicator includes a sleeve that loosely fits over the push rod of a pneumatic actuator.
U.S. Pat. No. 4,776,438 issued Oct. 11, 1988, discloses a brake adjustment indicator which includes a mounting bracket having an elongated body with a slot that runs parallel to a rod that extends through an air brake chamber and connects at one end to the brake arm by a clevis pin.
U.S. Pat. No. 4,879,964 issued Nov. 14, 1989, discloses an air brake adjustment marker that includes an air supply, an air canister, and moveable members that include a push rod that extends from the air canister and has a first extended position and a second over-extended position. The adjustment marker includes a chain attached to the push rod, and an indicator flag that is activated when the push rod is in the over-extended position.
U.S. Pat. No. 5,244,061 issued Sep. 14, 1993, discloses an air brake stroke length gage that operates in conjunction with an air brake system. The gage comprises of a stroke length indicator that is mounted on the push rod, and a reference marker that is attached to the air brake system at a distance which corresponds to the appropriate stroke length for the brake system when properly adjusted.
U.S. Pat. No. 5,320,198 issued Jun. 14, 1994, discloses a indicator for indicating the setting and linear stroke movement of a brake rod of a brake assembly. The gage includes reference indicators that are located on both the brake rod's clevis and on the arm of the brake's slack adjustment member, thereby indicating the brake rod travel and the need for brake adjustment.
U.S. Pat. No. 5,441,128 issued Aug. 15, 1995, discloses a bracket body that can be attached to a brake rod and to the clevis member of a conventional brake adjustment apparatus. The bracket body provides for an indirect measurement of the brake rod travel and adjustment.
Finally, Canadian patent application 2,186,271 which was laid open on Nov. 2, 1996 shows the use of a brake adjustment indicator including a mounting bracket, having an elongated body with a slot, and a spacer for receiving two bolts for indicating limit positions.